Geometric error identification and compensation of CNC machine tool based on KGM181

In consideration of the disadvantages of traditional measuring methods, a stepwise measurement and identification of machine geometric error method by using Cross Grid Encoder KGM181 is proposed in this paper, and a software module with the function of automatic compensation was made. Based on the theory of multi-body systems, geometric error model is established by using homogeneous coordinate transformation method. The transformational relation between the planed position and the real position is got by the model. A measuring strategy is introduced in this paper to get the deviations of the actual points and the desired points. There are two typical measuring routes in the strategy. One is the straight line along the direction of each axis and the other is the circular arc in x-y, y-z and z-x plane respectively. After the data processing and calculating, the geometric error coefficients can be identified which is used to predict the geometric error. Initializing the software module with the predicted error, then the NC code after error compensation will get. The effectiveness and feasibility of the compensation strategy is verified by experiment on Cross Grid Encoder. The geometric error is significantly reduced after compensation. In addition, the whole process can be completed within 2h means the strategy is very efficiency.